Competition Between Weak Localization and Antilocalization of Dirac‐Like Fermions in a Spin‐Polarized Two‐Dimensional Electron Gas at KTaO 3 (111) Interface
Hui Zhang, Daming Tian, Xiaobing Chen, Lu Chen, Min Li, Yetong Bai, Dengjing Wang, Fengxia Hu, Baogen Shen, Jirong Sun, Weisheng ZhaoABSTRACT
Quantum transport phenomena in two‐dimensional electron gases (2DEGs) at oxide interfaces have garnered significant interest owing to their potential in spintronic and quantum information technologies. Here, we systematically investigate the quantum conductance corrections of spin‐polarized 2DEGs formed at the interfaces between two insulating oxides, ferromagnetic EuTiO 3 (ETO) films and (111)‐oriented KTaO 3 (KTO) substrates. The anomalous Hall effect and hysteretic magnetoresistance provide evidence for long‐range ferromagnetic order in the 2DEGs, which could be attributed to interfacial Eu doping in combination with the magnetic proximity effect of the ETO layer. The breaking of time‐reversal symmetry by ferromagnetism in the 2DEGs, and with the assistance of the spin‐orbit coupling effect, leads to a non‐trivial Berry phase. These results are explained by the competition between weak localization (WL) and weak antilocalization (WAL) in quantum transport due to Dirac‐like fermions at the KTO (111) interfaces, strikingly similar to that observed in spin‐polarized 2DEGs in LAO/ETO/STO (111) heterostructures and magnetically doped topological insulators. Moreover, we find that this competition can be tuned by optical stimuli via a photo‐excitation‐induced shift of the Fermi level. Our findings demonstrate a controllable platform based on spin‐polarized oxide 2DEGs for quantum transport, opening new avenues for spin‐orbitronic and topological electronic applications.